Dear Dr. Geoff. I connected to the ethernet, green phone light lit.
Then disconnected and reconnected using wifi adapter, and it works!
Thank you so much for this simple tip. Why doesn't obihai have this as a troubleshooting tip for the 00 error code? In fact, I found no obihai info on this error code, only some helpers here making suggestions to the users, some helped, some didn't but none applied to my situation: unable to make calls after router was replaced.
Have a great Sunday.
Thank you again!
Bob